Low levels of patient health literacy may contribute to patients' difficulties following preventive and treatment regimens, leading to poor adherence and ultimately to poor health outcomes. Patient non-adherence (also called noncompliance) is a widespread problem in medical care, limiting opportunities to prevent the onset and/or progression of serious disease. The goal of this study is to employ the techniques of meta-analysis to systematically search, review, summarize, and integrate the statistical findings of all published research from 1948 through 2007 on the relationship between patient adherence and health literacy. This work will build on the Principal Investigator's existing databases of the adherence and health communication literatures from 1948-98. Calculation of multiple, conceptually driven meta-analyses will involve all health literacy conceptual definitions and measurement strategies in both observational and intervention studies. This work will examine the relationships between health literacy and adherence to recommendations from all health professionals (e.g., physicians, nurses) for both preventive and treatment regimens, including medication, diet, exercise, and all specific prevention and disease management efforts for a wide variety of acute and chronic conditions. These meta-analyses will examine the effects of moderators of the health literacy- adherence relationship, including patient characteristics (gender, ethnicity, age, education, economic status, and underserved status), disease conditions and treatment regimens, contexts of care, and research methodologies. This work will also examine trends over time in the development and evolution of substantive and methodological issues in health literacy and patient adherence. [unreadable] [unreadable] [unreadable]